For magnetic recording media represented by hard discs and the like, horizontal in-plane (or longitudinal direction) recording system has conventionally been adopted, but in such system disappearance of recording magnetization could occur as influenced by repulsion of magnetic poles, fluctuation of heat and so on, and high-density recording was difficult.
Due to these problems, perpendicular magnetic recording system is currently adopted, to effect higher density recording. In magnetic recording media of perpendicular magnetic recording system, frequently Co—Cr type alloy thin film such as of Co—Cr—Pt—Ta or the like is used, similarly to horizontal in-plane recording system, and coercive force of such a film is said to be normally 3-4 kOe.
Because Co—Cr type alloy thin film lacks thermal stability, it is attempted to prevent disappearance of recording magnetization caused by thermal fluctuation and the like, by adding thereto, for example, SiO2 to form a granular structure.
On the other hand, in order to suppress disappearance of recording magnetization under higher heat fluctuation and the like, development of Pt—Fe alloy film having high coercive force and magnetic anisotropy is attempted (for example, see JP 3305790). This Pt—Fe alloy film is usually made by sputtering or vapor deposition, but the resultant alloy film is in irregular state having face centered cubic (fcc) structure and must be converted to regular state having face centered tetragonal (fct) structure, for obtaining the alloy film having sufficient coercive force. For bringing about the regular state, normally a heat treatment is given.
Conversion of such irregular state to regular state (which is hereafter referred to as “regularization”) requires a heating treatment of the alloy film at temperatures not lower than 600° C. Hence aluminum or glass substrates which are deformed at 600° C. cannot be used, and a costly substrate such as of MgO, Si wafer, quartz and the like which are not deformed at 600° C. or higher must be used. Lowering of the regularization temperature, therefore, is in demand.